SD card holder.
remove vems v3 controller endplate (4 screws)
plug in SD card into the SD card holder
plug in the SD card holder PCB (2x5 connector) on the "ISPI" socket. The ISPI socket is 2x6 near the main processor. The 2 pins at the LM324 are not used. You can verify this on the SD card PCB (no trace to anywhere)
Click here for more info on software setup and usage
YouTube video about the installation